You can find the solution by plugging the x-value of each coordinate into the equation. It will be a solution if the y-value of the equation equals the y-value of the coordinate.
She will get 23 books. So, first, you take the shipping away to get $93.05, then you divide $93.05 by $3.95 which equals 23.55 and you can't have half a book; so it's 23!
